Blasting cabinet troubles.

[brightspark]

I'll check this.







I'm wondering what is the best bet as far as using the pressure pot or the Clemco type gun in the cabinet itself?
Thanks for the reply.

a pressure pot is far more powerfull than a suction gun thers no comparison

 

[dobbslc]

So the pressure pot is the way to go then?
I think I need to get some new house as the old stuff is a bit short and very stiff.

 

[dave h 2]

There should be a tank gauge on the auto on/off pressure electrical switch. That rotary switch should not be needed. I smell bodging, was the bloke you bought it off wearing spurs and a bit bandy legged?

 

[MetalMonkey]

Not a real issue to determine the flow from the compressor? It would appear a quite simple evaluation, to me. Particularly if it is a 10Bar machine and being run through a pressure regulator.

Likewise, easy enough to calculate the volume of air consumed by most air tools (which require up to a 6 Bar supply).

Ahh see, you would thinks so, but you are wrong, of course

You can have a situation where you may have the desired pressure at the end of the hose, but once you open the line you have significant drop as the regulator can't maintain pressure and flow enough - its known as droop.
A small amount is to be expected, but sometimes it can be significant enough to be an issue.

Likewise you can have issues with creep where the regulator will slowly over pressurise past the set point.
Hence why I suggested bypassing the tank regulator and connecting the hose directly to see if it eliminated it as a source of any problems.

 

[MetalMonkey]

I'm wondering what is the best bet as far as using the pressure pot or the Clemco type gun in the cabinet itself?

I'll defer to brightspark on the pressure pot as he is the guru on those things (I do know they aren't all rainbows and unicorns), but the Clemco style gun works well enough with the foot pedal and media mixer setup you have IME. Suction is going to be a slower process. I will say that there is a lot of variation in the quality of the Clemco clones, so that might also be a potential problem.

You seemed to be almost getting there with it on post #18 - so I suppose the first thing to establish is what changed?

 

[dobbslc]

You seemed to be almost getting there with it on post #18 - so I suppose the first thing to establish is what changed?

It did work but what I didn't realise was that it took a few minutes to blast that bit of metal in the picture and it should have been seconds.
I'll go have a clear up and do some of the basic checks you guys have mentioned as if the compressor is no good I'm just waiting my time.

 

[Wedg1e]

Your pump unit looks near-identical with that on my 3HP 100L SIP 'Workshop' range compressor that must be the neck end of 30 years old and can still build 140psi. I've had it 20+ years and apart from oil changes and cleaning the filter/ draining the condensate it's never needed looking at - and I've way exceeded the duty cycle a few times.
It will hold 80psi into my Guyson cabinet which with 80 grit AlOx is good enough for just about everything I've ever needed to blast.

 

[DaveB]

I think MetalMonkey is on to something.

We have two compressors at work with similar filter/regulator units and they both restrict the possible flow severely, I'm going to have to replace one once we're back next week.
They have too many plastic components and are easily damaged by people with no mechanical sympathy.

 

[brightspark]

Ahh see, you would thinks so, but you are wrong, of course

You can have a situation where you may have the desired pressure at the end of the hose, but once you open the line you have significant drop as the regulator can't maintain pressure and flow enough - its known as droop.
A small amount is to be expected, but sometimes it can be significant enough to be an issue.

Likewise you can have issues with creep where the regulator will slowly over pressurise past the set point.
Hence why I suggested bypassing the tank regulator and connecting the hose directly to see if it eliminated it as a source of any problems.

i never regulate my airline supply to the pot it operates between 90 psi and 120 and works well use 10.0mm bore pipe to feed the small one with c couplings / no loss of cfm

 

[KimB]

I run the same sized compressor with a similar cabinet but mine has the basic gun, like the one you got where it has a trigger on it.

My set up works really well other than the media often runs out because I don’t have the modified setup like you do. That being the Ali block at the bottom of the funnel and the better gun.

My compressor is in my shed which like others have said, I run it off the bung at the end of the compressor so I don’t lose pressure through the regulator. I then have it going through my air dryer that I made. It then goes underground In MDPE to my garage where I have a regulator/water separator connected to the cabinet.

That setup of mine works really well.

Also on the light front, I have a 10w LED flood light that I sit on the outside screen of the blasting cabinet, that really helps me see even when the screen starts fogging over.

 

[dobbslc]

I run the same sized compressor with a similar cabinet but mine has the basic gun, like the one you got where it has a trigger on it.

Not sure if you're referring to my set up Kim ^ but it does sound like I've got all the right gear but something isn't quite right.
I'll try to get that end bung out of the compressor tank then fathom out what size reducer will be needed to run the line direct.

 

[MetalMonkey]

How difficult do you think it is? It is simple.

It's even simpler if you actually bother to read the question.

The question is not about calculating theoretical flow, if you want to know that then it is far easier to look at the spec sheet in the manual.
The question is why the compressor and blaster aren't producing the expected results in practice.

Providing the compressor pumps up in a reasonable amount of time and cuts off, it is unlikely to be at fault.
The regulator is the next component in the chain, and easy to eliminate/test and cheaper to replace. All regulators will have a rated flow rate and will restrict flow to some degree.

If the compressor and regulator aren't the problem then the issue has to lie with the blast equipment, which in this case would mean both the pressure pot and the blast cabinet.

To reiterate, for the third time , just because the correct pressure is showing from a regulator with no demand, does not mean it will provide sufficient flow and maintain this pressure once the equipment is in use.
That is why they are made with different flow rates for different applications....

 

[MetalMonkey]

Not sure if you're referring to my set up Kim ^ but it does sound like I've got all the right gear but something isn't quite right.
I'll try to get that end bung out of the compressor tank then fathom out what size reducer will be needed to run the line direct.

One other thing that comes to mind which I should have mentioned earlier - make sure the blast media is appropriate and nice and dry with no large bits in it.
If it gets damp and starts clumping, or if it isn't suitable for the nozzle or has chunks in it, then it will clog up and you will be fighting a losing battle.

I have an old sieve I run mine through occasionally if I've got bits of rubbish in there which has flaked off a part.
With that type of mixing valve you only require a very small amount of media in the hopper.

 

[KimB]

Not sure if you're referring to my set up Kim ^ but it does sound like I've got all the right gear but something isn't quite right.
I'll try to get that end bung out of the compressor tank then fathom out what size reducer will be needed to run the line direct.

Sorry yes I was. The bung in mine had like a 1” or 3/4” thread in the centre of it I’m sure.

 

[dobbslc]

One other thing that comes to mind which I should have mentioned earlier - make sure the blast media is appropriate and nice and dry with no large bits in it.
If it gets damp and starts clumping, or if it isn't suitable for the nozzle or has chunks in it, then it will clog up and you will be fighting a losing battle.

I have an old sieve I run mine through occasionally if I've got bits of rubbish in there which has flaked off a part.
With that type of mixing valve you only require a very small amount of media in the hopper.

I've tried it with the media it came with (in the hopper, I did sieve it as it had paint in it) which looks like aluminium oxide, black and I'd say medium grade, I've also tried some glass bead that was in the pot although that's been in there for years so might be damp
I'll whip myself into action in a minute and time how long the tank takes to fill and see if I can get the end bung out...

 

[knighty]

you could unscrew that pressure regulator and put a T in under it... it'll come out easier than the end bung

sightly odd setup with the regulator bottom fed like that, I've not seen those before (not that I look at a lot of compressors tho)

 

[dobbslc]

Ok I've just timed the thing from empty to cut off at 8 bar / 120 PSI.
It took 11.5 minutes.
That's slower than the one linked to earlier in this thread.

 

[dave h 2]

Ok I've just timed the thing from empty to cut off at 8 bar / 120 PSI.
It took 11.5 minutes.
That's slower than the one linked to earlier in this thread.

Is it hissing excessively from the unloader valve before it goes quiet?

 

[JOEPRO]

Ok I've just timed the thing from empty to cut off at 8 bar / 120 PSI.
It took 11.5 minutes.
That's slower than the one linked to earlier in this thread.

There is something seriously wrong with your pump then! Have you owned this compressor from new or did you buy it used?

It should fill from empty in about 3 minutes in my opinion going by my own compressors. (One 200L 3hp SIP and a Tandem combined 6hp ABAC 300L)

The head Reed valves can fail or the head gasket can blow like what was the case on my used ABAC compressor I bought. One pump was doing all the work the other one was dead but "pumping" away.

 

[dobbslc]

Is it hissing excessively from the unloader valve before it goes quiet?

No it's fine.